Combination interlocking device



July 11, 1944. J v, scH R; 2,353,507

COMBINATION INTERLOGKING DEVICE Filed June s, 1945 2 Sheets-Sheet 1 INVENTOR. kmz: SCH/ems J. V. SCHRAIG COMBINATION INTERLOCKING DEVICE Filed June 3, 1943 UM/M 2 Sheets-Sheet 2 Patented July 11, 1944 UNITED STATES PATENT OFFICE COMBINATION INTERLOCKING DEVICE James V. Schraig, Central Valley, N. Y.

Application June 3, 1943, Serial No. 489,430

9 Claims. (Cl. 200-50) This invention relates to interlocking devices for use in combination with an electric switch and plug, and the main object thereof is to provide, in combination with a switch and a plug as well as the socket for the latter, an interlocking device'whichfunctions automatically to prevent closing of the switch when the plug is absent from its socket and to prevent withdrawal of the plug from its socket while the switch is closed.

The invention as herein presented is particularly adapted for marine application, but it may obviously be applied to any other field of application within the spirit and scope of the invention; and it is particularly to be noted that it is neither intended nor desired to limit the invention in any manner to the specific details of construction or operation set forth and illustrated, excepting as they may be deemed essential to the underlying principles of the invention.

The above and other objects will become apparent in the description below, wherein characters of reference refer to like-numbered parts in the accompanying drawings which form a part hereof.

Referring briefly to the drawings, Fig. 1 is a plan view of the device applied to the cover of an outlet or receptacle box, showing also the switch and the plug in relation thereto, with the switch in the off position.

Fig. 2 is a side View of Fig. 1.

Fig. 3 is a fragmentary view similar to Fig. 1 but showing the switch in the on position.

Fig. 4 is a fragmentary side view of Fig. 3.

Fig. 5 is a fragmentary plan view of the receptacle box cover per se.

Fig. 6 is a fragmentary plan view of the underside of the receptacle box cover.

Fig. 7 is an enlarged fragmentary cross-sectional view taken 0n the line 'I--I of Fig. 1.

Fig. 8 is a fragmentary enlarged cross-sectional view taken on the line 8-8 of Fig. 3.

Fig. 9 is a partial cross-sectional view similar to Figs. 7 and 8, but showing the relative positions of the mutually interlocking safety pin and slide bolt when the switch is in off osition, that is, when there is no plug in the socket.

Fig. 10 is a cross-sectional view taken on the line III-40 of Fig.7.

Referring in detail to the drawings, the numeral II indicates the removable cover of an outlet or receptacle box the outline of the inner surfaces of the walls of which is indicated at I2, the box, not otherwise shown, being separated by a partition I3 into two compartments I4 andv I5.

openings being separated by a partition 39.

Without going into unnecessary details regarding marine electrical practise, it should be sufficient to state that a pair of spaced openings are provided through the cover I I, one above and one below the line of the partition I3, the former being for the insertion of a plug I6 into the box and the latter for the mounting of a switch II, of the rotatable type. It should furthermore be unnecessary to illustrate or describe the electrical connections or interaction between the switch I I and the plug I6, for it is common marine practice that the switch I'I controls the supply of electrical current to the plug I6 through such connections, not shown, within the box I2.

An externally threaded peripheral flange I8 integrally surrounds the plug opening I9, and the plug I6, whose contact end is shown at 20, is provided with a knurled internally threaded collar or ring 2| which is adapted to screw down upon the flange I8 when the plug has been inserted, to lock the plug in place. The switch I7 is provided, externally of the box I2, with a peripherally deformed disc 22 parallel with the cover II, and with a web-like finger grip 23, extending diametrically therefrom at right angles thereto and at the same time serving as a pointer or indicator to show whether the switch is on or off. The peripheral deformation of the disc 22 comprises four quadrantial cam-like surfaces 24, 25, 25, and 21, spaced from each other serially by radial shoulders 28 and 29. It is to be noted that the radial length of each shoulder 28 is greater than that of each shoulder 29, thus forming in the peripheral edge of the disc 22 four notches, spaced a quadrant apart, the notches of one diametrically opposed pair, 28, being deeper than those of the other diametrically opposed pair, 29.

Formed on the cover I I between the aforementioned plug and switch openings therethrough, are a pair of spaced parallel platforms or lugs 30 having threaded holes 3| drilled down thereinto. A housing 32 having a raised central body 33 and a pair of lateral base members or wings 34, is-mounted on the lugs 30 with the Wings 34 resting on the lugs and the downwardly extending or projecting side walls 35 of the body 33 registering snugly between the lugs. Screws 35 secure the housing 32 in place.

A horizontal opening 31 extends longitudinally through the upper portion of the housing 3.2, and a second opening 38 similarly extends through the housing below the first, the two A vertical opening '40 through the latter provides communication between the two said horizontal openings. Near its lower end (Fig. 1), that is, adjacent the switch H, the opening 3'! is enlarged, as seen at 4|, and a peripheral shoulder 42 is thereby formed within the opening. A slide bolt 43 is slidably mounted in the opening 31, and has a collar 44 formed on one end, or near one end, thereof which registers slidably in the enlarged opening 4|. A coiled spring 45 surrounds the bolt 43 between this collarand the shoulder 42 and normally urges the bolt toward the left (Fig. 7). Near the other end of the bolt, a peripheral groove 46 is provided; the

at 41, and the right-hand wall or shoulder 48 thereof is convexly beveled.

A lever 49 is fulcrumed at one end on a pin 50 supported between the walls of the housing 32, and the other end thereof is deformed in a downward direction in Z-shaped fashion; a tongue 59 extends beyond the housing 32 from the extremity of the lever 49. A pin 5| is rigid on and extends upward from the lever 49 and registers slidably in the vertical opening this pin is of slightly less thickness or diameter than the opening 49, for reasons which will presently become apparent. A cone-shaped serration or tooth 52 is formed in the upper end of the pin 5| on that side thereof which faces the fulcrum end of the lever 49. A coiled compression spring 53 is mounted below the lever 49 at a position under the pin 5!, and is positioned by opposed vertical cylindrical grooves in the walls 35.

The plug H5 is of standard construction, and the ring 2| already mentioned, is loosely mounted on the cylindrical body 55 thereof. As so far described, it is apparent that the spring 53 normally urges the lever 49 upward about its fulcrum, and also urges the pin 5| upward through the opening 40. With the bolt 43 held in the position shown in Fig. 8, it is obvious that the bolt restrains the pin 5| from passing out through the top of the opening 40. The bolt 43 is held in that position when the switch I! is in the on position shown in Fig. 3, for then the tail end 56 of the bolt registers in one of the two shallower notches, 29, of the switch and this notch serves as a limit stop which prevents the spring from moving the bolt farther to the left (Fig. i

8). It is also seen that with the various parts in their respective positions just mentioned, the plug I! is in screwed home position, and in the act of screwing the ring 2| home on the flange N3 the ring has depressed the tongue and thus withdrawn the pin 5| down into the opening 45. Since as stated the tail of the bolt lies in a shallow notch 29 of theswitch, the bolt lies in its right-hand position (.Fig. 8) and hence its nose 5'! is projected out at the right to a position overlapping the ring 2 I, so that unscrewing of the ring is prevented. Thus, with the plug inserted and the switch I! closed, it is impossible to withdraw the plug.

In order to withdraw the plug it is first necessary to turn off the switch, and when the latter is done the bolt tail 56 will register in one of the notches 28, that is, a deeper notch. Since this notch permits farther movement of the bolt to the left (Fig. 7), the bolt nose 5'! is withdrawn from its position of obstruction to the unscrewing, or raising, of the ring 2|, whence the plug may be removed. As the plug ring 2| is being unscrewed, the tongue -50 rises part way into the groove 46 of the bolt, as can be surmised from Fig. 7. Upon any attempt to turn the switch on. it is obvious that the bolt will be stopped in its movement toward the right (Fig. 7) by engagement of the pin 5| in the bolt groove 46, which in the extreme right-hand position of the bolt in such an attempt to turn on the switch when the plug H is not screwed home causes positive interlocking between the tooth 52 and the dishedout wall 41 of the groove. It is thus apparent that movement of the switch to on position in such a case is impossible.

It should be mentioned that in turning the switch I! through a quadrant from the off to the on position or vice versa, the tail 56 of the bolt rides upon the cam surfaces, or rather on one of the cam surfaces 24, 25, 26, or 21, and it is just before the tail 56 reaches the hump of such a surface that the bolt is restrained from further movement to the right in an attempt to turn on the switch when there is no plug in the plug opening l9. It is further to be noted that the switch I! can be turned only in the direction of the arrows in Figs. 1 and 3.

The devic presented thus prevents unscrewing of the plug from its socket while the switch is on and also prevents turning the switch on" before the plug has been inserted and screwed home into its socket.

Obviously, modifications in form and structure may be made without departing from the spirit and scope of the invention.

In Fig. 6 is shown the standard slot and tongue engagement by which the plug |6 cannot be shoved down excepting in the correct position. The lower body portion 58 of the plug has a vertical slot 50 in the front wall thereof. A tongue 69, extending into the plug opening I9 of the cover H, is part of a member 6| which is secured to the underside of the cover.

I claim:

1. In combination, a support having a plug receptacle therein, an electrical switch mounted on said support and spaced from said receptacle, a plug insertible into said receptacle and having a ring mounted on the body thereof, a housing mounted between said switch and receptacle and having a bolt slidably mounted therein with its axis extending substantially in the direction of a line joining the axes of said switch and said receptacle, said bolt being of greater length than said housing, said switch including a rotatable member substantially parallel with said support, resilient means normally urging said bolt into contact with the peripheral edge of said member, said member having cam-like surfaces formed on said peripheral edge and having radial notches separating said surfaces from each other, the radial depth of said notches being alternately greater and lesser serially around said peripheral edge, one end of said bolt normally registering in one of said notches, the other end of said bolt extending farther out of said housing when said first end registers in one of said shallower notches than when said bolt registersin one of said deeper notches, said other end of said bolt when said bolt registers in one of said deeper notches lying outside the geometrical projection of the periphery of said receptacle and projecting into said geometrical projection and overlapping said ring when said bolt registers in one of said shallower notches, said plug in the latter condition of said bolt being restrained from withdrawal from said receptacle, said switch and bolt being synchronized so that said switch is in the on position when said bolt registers in one of said shallower notches and in the off position when said bolt registers in one of said deeper notches.

2. The combination set forth in claim 1, having in addition tripping means mounted in said housing, said bolt having means interlocking with said tripping means to prevent sliding of said bolt from said position where said other end thereof lies outside said geometrical projection to the position where said other end projects thereinto when said plug is absent from said receptacle, said tripping means extending beyond the housing at that end adjacent said receptacle and lying in the path of said ring while said plug is being inserted and being depressed by said ring to release said bolt when said plug has been inserted into said receptacle to permit said bolt to be slid into said overlapping position with respect to said ring.

3. The combination set forth in claim 1, having in addition a lever pivotally mounted in said housing and having one end thereof extending beyond that end of said housing adjacent said receptacle, resilient means normally urging said extending end of said lever upward from said support, said bolt having a peripheral groove therein, a pin extending from said lever and normally urged into said groove when said bolt registers in one of said deeper notches, said ring upon insertion of said plug engaging said lever extension and forcing the same downward toward said support and withdrawing said pin from said groove.

, 4. The combination set forth in claim 1, having in addition a raised externally threaded flange surrounding said receptacle, said ring being loosely mounted on said plug and having internal threads thereon engageable with said flange threads.

5. The combination set forth in claim 1, having in addition interlocking means comprising a pin normally urged against said bolt, said bolt having a deformed portion, said pin normally engaging said deformed portion of said bolt to restrain said bolt from movement into said geometrical projection, and tripping means comprising a lever having said pin mounted thereon and resilient means normally urging said lever upward from said support and providing the means for said normally urging of said pin toward said bolt.

6. In combination, a pair of spaced apart members, a support, one of said members being rotatably mounted on said support and the other being slidably mounted thereon, a third member mounted between said first members and having a bolt slidably mounted therein in the direction of a line drawn between said first members, said slidable member having a pair of spaced shoulders thereon, latching means associated with said bolt having a tongue extending from that end of said third member adjacent said slidable member, said bolt being slidable from a position in which one end thereof extends beyond its adjacent end of said third member to a position in which the other end thereof extends from the other end of said third member, said rotatable member having means upon rotation for sliding said bolt from one of said positions thereof to the other, said bolt having resilient means for restoring said bolt from the first to the second of said positions upon further rotation of said rotatable member, said latching means normally locking said bolt against slidable movement, one of said spaced shoulders releasing said latching means by contacting said tongue upon slidable insertion thereof onto said support to permit sliding of said bolt by said rotation of said rotatable member, said lastnamed sliding of said bolt moving said one end thereof to a position overlapping said other shoulder to lock said slidable member on said support.

7. The combination set forth in claim 6, wherein said resilient means on said bolt restores said bolt to its position before said last-named sliding thereof upon further rotation of said rotatable member to unlock said slidable member.

8. The combination set forth in claim 1, having in addition a lever pivotally mounted in said housing and having one end thereof extending beyond that end of said housing adjacent said receptacle, resilient means normally urging said extending end of said lever upward from said support, said bolt having a peripheral groove therein, a pin extending from said lever and normally urged into said groove when said bolt registers in one of said deeper notches, said ring upon insertion of said plug engaging said lever extension and forcing the same downward toward said support and withdrawing said pin from said groove, peripheral walls on the sides of said bolt groove, that one of said walls which faces toward said switch being dished out conically, said pin having a complementary tooth on the upper end adapted to register in said dished out wall after a partial movement of said bolt in the direction toward said receptacle when said plug is absent from said receptacle to lock said bolt against completion of said movement.

9. The combination set forth in claim 1, having in addition tripping means mounted in said housing, said bolt having means interlocking with said tripping means to prevent sliding of said bolt from said position where said other end thereof lies outside said geometrical projection to the position where said other end projects thereinto when said plug is absent from said receptacle, said tripping means extending beyond the housing at that end adjacent; said receptacle and lying in the path of said ring while said plug is being inserted and being depressed by said ring to release said bolt when said plug has been inserted into said receptacle to permit said bolt to be slid into said overlapping position with respect to said ring, said interlocking means comprising a pin normally urged against said bolt, said bolt having a deformed portion, said pin normally engaging said deformed portion of said bolt to restrain said bolt from movement into said geometrical projection, tripping means comprising a lever having said pin mounted thereon, and resilient means normally urging said lever upward from said support and providing the means for said normally urging said pin toward said bolt.

JAMES V. SCI-IRAIG. 

